The present invention relates generally to a layout for an antena. More particularly, the present invention relates primarily to a layout for a radio frequency (RF) antena. An example of a RF antena is a window antena for a vehicle or other automotive means.
Modern automotive means may need an antenna to support RF communication. A number of devices may function using RF communication. For m instance, AM radios, FM radios, AM/FM radios, CB radios, cellular phones, and global positioning systems are dependent on RF communication.
A modern automobile may have a glass window that serves as a dielectric support for a wire pattern layout of a RF antenna. Typically, a rear window is used for such purposes. A pattern of wires printed or imbedded in the glass (i.e., printed lines) may permit RF current flow to and from the desired RF device.
The rear window of a typical automobile also has a pattern of printed lines that enables DC current flow. DC current causes these printed lines to act as heating elements. As a result, these lines may be used to defrost or defog the rear window, thereby enabling a driver to see out the rear window. To adequately serve this purpose, the heating elements typically cover a substantial area of the rear window. As a result, there is usually insufficient area for an isolated wire pattern layout for a traditional RF antenna. Consequently, the heating elements interfere with operation of the traditional RF antenna, causing the traditional RF antenna to exhibit relatively poor pattern control and impedance matching over the desired frequency band.
The present invention provides an improved layout for an antenna. The antenna design of present invention takes into account the characteristics of RF current flow and the impact of a heater grid pattern. As a result, exemplary embodiments of the present invention provide improved directional gain patterns and impedance characteristics as compared to traditional window antenna designs.
One embodiment of a wire pattern layout comprises a plurality of power wires and an antenna wire. The power wires are adapted to, be in electrical communication with a power source, e.g., a DC power source. An example of the power wires includes, but is not limited to, the printed lines of a heater grid pattern. The power wires may be arranged in any desired pattern. In a common heater grid pattern, the power wires are arranged in approximately parallel rows. The antenna wire traverses some or all of the power wires. In one embodiment, the antenna wire has a configuration that extends at an oblique angle across the power wires. In other words, an imaginary axis or generally central line of the configuration extends at an oblique angle across the power wires. There may be at least one change of direction of the configuration as the antenna wire extends across the power wires. The antenna wire is adapted to be in electrical communication with a feed to a radio frequency device.
The shape of the antenna wire may be selected to achieve optimal pattern control and impedance characteristics. In one exemplary embodiment, the antenna wire has a substantially straight line configuration. In another exemplary embodiment, the configuration of the antenna wire is a step pattern. The angle of each step may be selected to achieve the optimal antenna characteristics. The inventors have discovered that steps of about 90 degrees may be preferred in some embodiments to prevent or limit interference with the heater grid power flow. In other words, the antenna wire may intersect each power wire at an angle of approximately 90 degrees to limit interference with the heater grid power flow. For optimal results in some embodiments, there may be at least one change in direction of the antenna wire. For instance, a straight line may change directions, or a step pattern may change directions. In one exemplary embodiment, the antenna wire may have a xe2x80x9cVxe2x80x9d or xe2x80x9cWxe2x80x9d shape. Of course, some embodiments of the present invention may include at least one additional antenna wire that is also adapted to be in electrical communication with the feed to the radio frequency device. Each additional antenna wire may include any of the optional or preferred features of the above-described antenna wire.
The wire pattern layout may be supported by any suitable means. For example, the power wires and the antenna wire(s) may be printed lines that are supported by at least one dielectric panel. One example of a dielectric panel is an automotive window.
The antenna wire(s) may be adapted to be in electrical communication with any suitable device. For instance, the antenna wire(s) may be connected to a suitable RF device. Examples of RF devices include, but are not limited to, AM radios, FM radios, AM/FM radios, CB radios, global positioning systems, cellular phones, and various combinations of such devices.
The present invention includes another embodiment of a wire pattern layout for an antenna. This embodiment may include any of the optional or preferred features of the other embodiments of the present invention. In this embodiment, the wire pattern layout comprises at least one dielectric panel that supports a plurality of power wires, an antenna feed, and a plurality of antenna wires. The power wires are in electrical communication with a power source, and the feed is in electrical communication with a radio frequency device. The antenna wires are in electrical communication with the feed. At least one of the antenna wires has a configuration that extends at an oblique angle across the power wires.
Yet another embodiment of a wire pattern layout for an antenna is included in the present invention. This embodiment may include any of the optional or preferred features of the other embodiments of the present invention. This example of the wire pattern layout comprises an antenna feed and two wire arrays. The feed is adapted to be in electrical communication with a radio frequency device. The first wire array is in electrical communication with the feed. The first wire array comprises a plurality of intersecting antenna wires. In one exemplary embodiment, the first wire array may also include an additional antenna wire that extends at least partially around the second wire array. The second wire array comprises a plurality of power wires and at least one antenna wire. The first wire array may be electromagnetically coupled to the antenna wire(s) of the second wire array. In one example, a coupling wire may be connected to the first wire array, wherein the coupling wire facilitates electromagnetic coupling of the first wire array to the antenna wire(s) of the second wire array. The power wires are adapted to be in electrical communication with a power source, and the antenna wire(s) of the second wire array traverse the power wires. In one exemplary embodiment, an antenna wire of the second wire array may have a configuration that extends at an oblique angle across the power wires. In other embodiments, an antenna wire of the second wire array may be a straight line that is perpendicular to the power wires.
The antenna wires of the first array may intersect in any suitable pattern. In one embodiment, the intersecting antenna wires of the first wire array may include a plurality of approximately horizontally oriented antenna wires and at least one approximately vertically oriented antenna wire. The approximately vertically oriented antenna wire may traverse some or all of the approximately horizontally oriented antenna wires. As in previously described embodiments, the antenna wires of the first and second wire arrays may include any suitable shapes. In an exemplary embodiment, the first and second wire arrays are supported by a window of an automobile, and the first wire array is situated above and substantially adjacent to the second wire array.
In another embodiment of the present invention, a wire pattern layout for an antenna comprises two antenna wires that are coupled together. A feed is adapted to be in electrical communication with a radio frequency device. A first antenna wire is in electrical communication with the feed. The second antenna wire is included in a wire array. The wire array also includes a plurality of power wires that are adapted to be in electrical communication with a power source. The second antenna wire intersects the power wires, and it is electromagnetically coupled to the first antenna wire. This embodiment of the present invention may also include any of the optional or preferred features of the other embodiments of the present invention.
The present invention includes another embodiment of an antenna layout. This example may include any of the optional or preferred features of the other embodiments of the present invention. In this example, a feed is adapted to be in electrical communication with a radio frequency device. A metallic film is in electrical communication with the feed. A wire array may also be included. The wire array comprises a plurality of power wires, and it is adapted to be in electrical communication with a power source. The metallic film and the wire array are supported by at least one dielectric panel.
Another embodiment of the present invention includes a first dielectric panel that is connected to a second dielectric panel. An antenna is supported by the first dielectric panel, whereas the second dielectric panel supports a heater layout. The heater layout may comprise a plurality of power wires adapted to be in electrical communication with a power source. The dielectric panels may be comprised of any suitable dielectric materials. In one example, the first dielectric panel is comprised of plastic, and the second dielectric panel is comprised of glass. Some other examples of dielectric materials include, but are not limited to, safety glass, polycarbonate, plexiglass, and fiberglass. In addition, this embodiment may include any of the optional or preferred features of the other embodiments of the present invention.